1. ME 123 Computer Applications I Lecture 15: More Matlab Programming: Root Finding 4/3/03

2. ME 123 Computer Applications I
Reminder
Program 2 is due on Friday before class
Exam 1 will be on next Monday.
Lecture 15
ME 123 Computer Applications I

3. Recapitulation of Lecture 14
In the last lecture, we learned the while loop and switch statement
Homework feedback:
Pay attention to the ending value of your time marching variable. If the upper limit of your for loop is x_end, the Explicit Euler will give you a value at x = x_end + step_size upon completion of the loop.
When you define a variable, make sure it is consistently a scalar or a vector throughout the program. Some of your programs switch between the two!
Advice to your programming:
Work out the problem by hand first. If you don’t know the procedure, you cannot give correct instructions to the computer! I guarantee it. You immediate task would be to understand the problem first, not the programming!!
Lecture 15
ME 123 Computer Applications I

4. ME 123 Computer Applications I
Road Map of Lecture 15
Solutions to HW 4-2
More Matlab programming exercise: root finding
the bisection method: cut the bounding interval in half each time until the required accuracy is achieved
work out flow chart with students and emphasize its importance
emphasize sequential thinking in programming
Lecture 15
ME 123 Computer Applications I

5. “Crude” Flow Chart for Bisection
Input left and right bounds no
Check to make sure they bound the root (How?)
yes
Compute the mid-point
Check if the mid-point and the lower bound sandwich the root (How?)
yes no
upper bound = mid-point
lower bound = mid-point
Lecture 15
ME 123 Computer Applications I